diff --git a/input/day07.txt b/input/day07.txt
new file mode 100644
index 0000000..eb586e7
--- /dev/null
+++ b/input/day07.txt
@@ -0,0 +1,101 @@
+Step B must be finished before step K can begin.
+Step F must be finished before step I can begin.
+Step T must be finished before step U can begin.
+Step R must be finished before step Z can begin.
+Step N must be finished before step S can begin.
+Step X must be finished before step Y can begin.
+Step I must be finished before step Y can begin.
+Step K must be finished before step L can begin.
+Step U must be finished before step J can begin.
+Step G must be finished before step L can begin.
+Step W must be finished before step A can begin.
+Step H must be finished before step Q can begin.
+Step M must be finished before step L can begin.
+Step P must be finished before step L can begin.
+Step L must be finished before step A can begin.
+Step V must be finished before step Y can begin.
+Step Q must be finished before step Y can begin.
+Step Z must be finished before step J can begin.
+Step O must be finished before step D can begin.
+Step Y must be finished before step A can begin.
+Step J must be finished before step E can begin.
+Step A must be finished before step E can begin.
+Step C must be finished before step E can begin.
+Step D must be finished before step E can begin.
+Step S must be finished before step E can begin.
+Step B must be finished before step R can begin.
+Step U must be finished before step O can begin.
+Step X must be finished before step I can begin.
+Step C must be finished before step S can begin.
+Step O must be finished before step S can begin.
+Step J must be finished before step D can begin.
+Step O must be finished before step E can begin.
+Step Z must be finished before step O can begin.
+Step J must be finished before step C can begin.
+Step P must be finished before step Y can begin.
+Step X must be finished before step S can begin.
+Step O must be finished before step Y can begin.
+Step J must be finished before step A can begin.
+Step H must be finished before step C can begin.
+Step P must be finished before step D can begin.
+Step Z must be finished before step S can begin.
+Step T must be finished before step Z can begin.
+Step Y must be finished before step C can begin.
+Step X must be finished before step H can begin.
+Step R must be finished before step Y can begin.
+Step T must be finished before step W can begin.
+Step L must be finished before step O can begin.
+Step G must be finished before step Z can begin.
+Step H must be finished before step P can begin.
+Step I must be finished before step U can begin.
+Step H must be finished before step V can begin.
+Step N must be finished before step Y can begin.
+Step Q must be finished before step E can begin.
+Step H must be finished before step D can begin.
+Step P must be finished before step O can begin.
+Step T must be finished before step I can begin.
+Step W must be finished before step V can begin.
+Step K must be finished before step M can begin.
+Step R must be finished before step W can begin.
+Step B must be finished before step T can begin.
+Step U must be finished before step A can begin.
+Step N must be finished before step H can begin.
+Step F must be finished before step U can begin.
+Step Q must be finished before step O can begin.
+Step Y must be finished before step S can begin.
+Step V must be finished before step O can begin.
+Step W must be finished before step C can begin.
+Step Y must be finished before step J can begin.
+Step T must be finished before step V can begin.
+Step N must be finished before step D can begin.
+Step U must be finished before step Q can begin.
+Step A must be finished before step C can begin.
+Step U must be finished before step M can begin.
+Step Q must be finished before step S can begin.
+Step P must be finished before step V can begin.
+Step B must be finished before step Z can begin.
+Step W must be finished before step Q can begin.
+Step L must be finished before step S can begin.
+Step I must be finished before step P can begin.
+Step G must be finished before step P can begin.
+Step L must be finished before step C can begin.
+Step K must be finished before step A can begin.
+Step D must be finished before step S can begin.
+Step I must be finished before step H can begin.
+Step R must be finished before step M can begin.
+Step Q must be finished before step D can begin.
+Step K must be finished before step O can begin.
+Step I must be finished before step C can begin.
+Step N must be finished before step O can begin.
+Step R must be finished before step X can begin.
+Step P must be finished before step C can begin.
+Step B must be finished before step Y can begin.
+Step G must be finished before step E can begin.
+Step L must be finished before step V can begin.
+Step W must be finished before step Y can begin.
+Step C must be finished before step D can begin.
+Step M must be finished before step J can begin.
+Step F must be finished before step N can begin.
+Step T must be finished before step Q can begin.
+Step I must be finished before step E can begin.
+Step A must be finished before step D can begin.
diff --git a/src/main.rs b/src/main.rs
index 06fcc20..4069f6a 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,4 +1,4 @@
 fn main() {
-    // aoc_2018::tasks::day06::task1();
-    aoc_2018::tasks::day06::task2();
+    aoc_2018::tasks::day07::task1();
+    // aoc_2018::tasks::day07::task2();
 }
diff --git a/src/tasks/day07.rs b/src/tasks/day07.rs
new file mode 100644
index 0000000..e54c704
--- /dev/null
+++ b/src/tasks/day07.rs
@@ -0,0 +1,42 @@
+use crate::utils;
+use std::collections::{HashMap, HashSet};
+
+pub fn task1() {
+    let input = utils::read_file("input/day07.txt");
+    let mut tasks: HashSet<char> = HashSet::new();
+    let dependencies: Vec<(char, char)> = input
+        .lines()
+        .map(|line| (line.chars().nth(5).unwrap(), line.chars().nth(36).unwrap()))
+        .collect();
+
+    let mut depends_on: HashMap<char, HashSet<char>> = HashMap::new();
+    for (a, b) in dependencies {
+        depends_on.entry(b).or_insert(HashSet::new()).insert(a);
+        tasks.insert(a);
+        tasks.insert(b);
+    }
+
+    let mut open: HashSet<char> = tasks
+        .iter()
+        .filter(|task| !depends_on.contains_key(task))
+        .map(|c| *c)
+        .collect();
+
+    let mut result = String::new();
+    while open.len() > 0 {
+        let next = open.iter().min().unwrap().clone();
+        open.remove(&next);
+        result.push(next);
+        let newly_open: HashSet<char> = depends_on
+            .iter()
+            .filter(|(task, deps)| deps.iter().all(|dep| result.chars().any(|c| c == *dep)))
+            .map(|(task, _)| *task)
+            .collect();
+        open = open.union(&newly_open).map(|c| *c).collect();
+        for c in newly_open {
+            depends_on.remove(&c);
+        }
+    }
+
+    println!("{}", result);
+}
diff --git a/src/tasks/mod.rs b/src/tasks/mod.rs
index d945a75..58e7837 100644
--- a/src/tasks/mod.rs
+++ b/src/tasks/mod.rs
@@ -4,3 +4,4 @@ pub mod day03;
 pub mod day04;
 pub mod day05;
 pub mod day06;
+pub mod day07;